1. Field of the Invention
The present invention is broadly concerned with reducing apparatus of the type typically used in the production of chunk-type products, e.g., meats used in chilies, stews and as pizza toppings. More particularly, it is concerned with an improved jet-knife apparatus which makes use of a continuous stream of steam or pressurized air in order to forcibly expel product through an apertured plate.
2. Description of the Prior Art
A wide variety of reducing or comminuting devices have been used in the past to comminute and subdivide meat and other products. These devices vary in complexity and sophistication, depending upon the ultimate product desired. In cases where chunk-type products are to be produced, it has been known to provide grinders equipped with a large circular grinder plate having a series of apertures therethrough, in conjunction with a rotatable, multiple bladed grinder knife. In these devices, incoming product is fed towards and through the grinder plate, and the rotating knife serves to cut the product to a desired size.
In another type of known device, the respective blades are provided with elongated fluid-conveying recesses or channels along the length thereof, and means is provided for delivery of steam or pressurized air to such channels. During rotating of the knife, the blades come into communication with the plate apertures, and the pressurized steam or air expels or "pops" the product from the apertures. This kind of device has been referred to as a "jet-knife" grinder, and has been used in the production of chunk-type meat products.
A prime drawback of prior jet knife assemblies, however, resides in the fact that they are prone to the production of fines or extra long strings of agglomerated meat particles. Fines in this context refers to particles too small for practical use, whereas strings refers to elongated strands of meat likewise not in optimum condition for use. Fines are typically produced by over-pressurization at the plate apertures, whereas strings result from low pressure conditions at the apertures. Such unwanted differential pressures at different apertures may result when a given knife blade channel bridges more than one plate opening during rotation, with the combined areas presented by the opening being greater than the cross-sectional area of the knife blade channel. In these situations product can momentarily hang up in the apertures until further fluid pressure is developed in the channel as a result of the blade rotating to a position where the channel cross-sectional area exceeds that of the bridged open areas of the plate; at this point the product may be forcibly ejected from the plate with great velocity, resulting in fines. On the other hand, product hang-up can also cause agglomeration of product within the plate apertures and resultant strings. In short, the problem of pressure differences at the plate apertures can under varying circumstances lead to serious operational problems.
A related difficulty stems from the fact that, with prior jet knife arrangements, the knife operating face on either side of the channel is of insufficient width to completely cover all apertures as the knife rotates. Thus, situations can arise where a given aperture is simultaneously subjected to fluid pressure and to pressure from the stream of product directed towards the plate. This again leads to uneven pressures and the types of problems described above.